Individually sealing quantities of a product in a package provides substantial advantages for packaging products that are sensitive to exposure to air. This is particularly advantageous for pre-sliced food products, such as cheese.
Known techniques for individually wrapping slices of a product are exemplified by U.S. Pat. No. 3,542,570 to Bush et al. and U.S. Pat. No. 3,162,539 to Repko. Packages of individually wrapped packages have enjoyed substantial market success due to their increased home shelf life, even in spite of the greater cost of such packaging. In the above-mentioned patents, each slice of product is dispensed in a wrapper which completely encloses the slice of product. When these wrapped slices are stacked to form a package of slices, at least two layers of wrapper are positioned between two adjacent slices of product, and the stack of individually wrapped slices are enclosed in still a further over-wrapper.
The type of wrapping material used in overwrapping such packages of cheese slices, for example, is an expensive laminated, coextruded or coated film including at least one layer of an oxygen impermeable material. It should be noted though that many individually wrapped cheese slices on the market today are hermetically sealed only by the overwrapper. The wrappers on the individual slices generally are not hermetically sealed. Thus, when the overwrapper is opened the slices tend to dry and to mold, although the process is significantly slowed by the individual wrappers.
Other prior art packaging systems utilize a continuous interleaf sheet which covers both faces of each slice of product in a stack and is alternately folded over one edge of each slice. This is illustrated in U.S. Pat. No. 2,635,965 to Hensgen et al., U.S. Pat. No. Re. 26,493 to Stoker, and U.S. Pat. No. 3,051,584 to Tindall. These patents show a single layer of wrapping material between adjacent food slices which facilitates separation of the slices and uses less interleaf film than individually wrapped slices but each slice of product is not individually sealed. Another prior art patent that also shows the use of an interleaf sheet between adjacent slices of product is Seifert et al. U.S. Pat. No. 3,730,739. The Seifert patent uses separate interleaf sheets to aid in dispensing the product, but, again, has the disadvantage that individual slices of product are not separately sealed.
Using a somewhat related approach to the individual wrapping system, Edwards U.S. Pat. No. 3,325,000 discloses a package for cigars wherein each cigar is in an individual compartment defined by a supporting tray that borders each article on both ends and three sides, and a cover sheet which can be removed to expose an individual cigar. This configuration has numerous disadvantages including not reducing the package size as each article is dispensed. Additionally, it is less economical to have a rigid supporting tray bordering each article on three sides. In another embodiment in the Edwards patent, each article is individually sealed by a tray that borders the article on both ends and three sides, and is releasably frictionally secured to one wall of an adjacent tray. This embodiment also has the disadvantages that each severable tray seals a single cigar, rather than forming an additional seal around all remaining cigars, and is less economical since it requires each article to be enclosed in a rigid tray.